Search for an Axionlike Spin Coupling Using a Paramagnetic Salt with a dc SQUID

We use a paramagnetic salt ${\mathrm{TbF}}_{3}$ with a dc SQUID to search for a possible axionlike $\mathit{\ensuremath{\sigma}}\ifmmode \dot{}\else \.{}\fi{}\mathbf{r}$ interaction of a rotating copper mass with the salt. We set new limits on the axion coupling constant ${g}_{s}{g}_{p}/\ensuremath{\Elzxh}c$ and the finite-range Leitner\char21{}Okubo\char21{}Hari Dass coupling constant $A$. Our limit for range $\ensuremath{\lambda}$ at 30 mm is 2 orders of magnitude better than previous results. For $\ensuremath{\lambda}g30\mathrm{mm}$, ${g}_{s}{g}_{p}/\ensuremath{\Elzxh}c$ is $(0.14\ifmmode\pm\else\textpm\fi{}0.67)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}28}$, and $A$ is less than 10. The outlook for further improvement is discussed.